The present invention relates to a spinneret for melt spinning a plurality of strand-like filaments, of the general type disclosed, for example, in DE 199 32 852 A1.
A known spinneret of this type comprises a housing, which is used to accommodate a spinneret plate, an apertured plate, a filter insert, as well as an inlet component. The spinneret plate, the apertured plate, and the inlet component are inserted into the housing, and held inside the housing by a threaded member. The internal parts of the housing are made of a material, which has a higher coefficient of thermal expansion than the housing material. With that, it is accomplished that in the operating state of the spinneret, which could be, for example, in an area of 300° C., the internal parts expand inside the housing to a greater extent than the housing surrounding the internal parts. This causes a pressure force to develop, which results in sealing the separating lines between the internal parts or between the internal parts and the housing.
However, the known spinneret has the disadvantage that it always requires the use of different materials for making housing components and internal housing parts of the spinneret. Furthermore, the selection of the materials for the internal parts also requires taking into account an adequate strength and resistance to the polymer melt that is to be processed. With that, only materials are considered, which have a small difference in the thermal expansion coefficients. In this respect, the known spinneret is suited only for very high operating temperatures to generate an adequate sealing effect.
DE 199 35 982 A1 likewise discloses a spinneret, wherein a housing accommodates a filter insert and a spinneret plate. In this spinneret, the spinneret plate is held in the housing by way of a threaded connection. Likewise in this instance, the internal parts are made of materials, which have a greater thermal expansion coefficient than the housing. In this respect, the foregoing disadvantages occur in the same way. In addition, the assembled condition requires that the greater thermal expansion of the internal parts relative the housing requires building up both radially active and axially active forces of pressure.
DD 125421 discloses a spinneret, wherein the spinneret plate and an apertured plate are arranged inside a sleeve, which is mounted by a threaded member to the end face of a housing portion that forms the melt inlet. Between the end face of the housing portion and the attached apertured plate and spinneret plate, a seal is arranged within the sleeve that accommodates the internal parts. The sleeve is made of a material which has a higher thermal expansion coefficient relative to the housing component and the threaded member for purposes of achieving during the heating of the sleeve, a deformation of the seal arranged between the parts, and with that a self-sealing effect. This known spinneret has the disadvantage that the internal parts of the spinneret are inserted directly into a housing component that expands to a greater extent. While taking into account the thermal expansion, it is therefore necessary to insert the internal parts with a corresponding play, which has, however, a negative effect on the required accurate fit for sealing the separating lines.
It is an object of the invention to further develop a spinneret of the initially described type in such a manner that the internal parts that are combined with an accurate fit inside a housing, are held in a self-sealing manner substantially independently of their materials.